Semiconductor elements such as IC's and LSI's and liquid-crystal panel elements are produced by evenly applying a photoresist to an electroconductive film of a metal, e.g., aluminum, copper, or an aluminum alloy, formed on a substrate or to an insulating film, e.g., SiO.sub.2 film, formed on a substrate, light-exposing the resist layer or drawing an image thereon with an electron beam, subsequently developing the resist layer to form a resist pattern, selectively etching the electroconductive metal film or insulating film using the pattern as a mask to form a fine circuit, and then removing the unnecessary resist layer with a remover solution.
Conventionally used resist remover solutions for removing resist include organic sulfonic acid-based remover solutions containing an alkylbenzenesulfonic acid as an essential component and organic amine-based remover solutions containing an organic amine, e.g., monoethanolacine, as an essential component. However, the organic sulfonic acid-based remover solutions have a drawback that since they contain a highly toxic organic solvent, such as a phenol compound or chlorobenzene, not only use of the remover solutions results in poor working efficiency and poses an environmental problem, but also the remover solutions are apt to corrode electroconductive metal films on substrates and the like. In contrast, the organic amine-based remover solutions are less toxic than the organic sulfonic acid-based remover solutions, do not require a troublesome wastewater treatment of the organic sulfonic acid-based remover solutions, are effective in removing modified films resulting from treatments such as dry etching, ashing, ion implantation, and the like, and are highly inhibited from corroding substrates having provided thereon Al, Cu, and the like. Because of these advantages, the organic amine-based remover solutions are currently used extensively.
However, as a result of the recent trend toward severer conditions for treatments such as dry etching, ashing, ion implantation, and the like in processes for producing semiconductor elements or liquid-crystal panel elements, these treatments have come to modify originally organic resist films to films having inorganic properties. The modified films cannot be sufficiently removed even with organic amine-based remover solutions. Another drawback of organic amine-based remover solutions is that since they are used at a relatively high temperature of 60 to 130.degree. C., there is a danger that the flammable organic compounds contained therein volatilize and catch fire. Consequently, the removing treatment is generally performed in an inflammation-preventive apparatus, and requires much equipment cost. In addition, since this prior art removing treatment using the organic amine-based remover solution takes much time, the remover solutions becomes unsatisfactory for use in the production of semiconductor elements and liquid-crystal panel elements in which a high throughput (the number of wafers treated per unit time) is required. Remover solutions usable at a low temperature (room temperature) are disclosed in JP-A-64-88548 and JP-A-5-259066 (the term "JP-A" as used herein means an "unexamined published Japanese patent application"); however, both of them contain an organic amine and water and hence has drawbacks of insufficient removing performance and a strong tendency to corrode substrates.
Under these circumstances, the present: inventors proposed in JP-A-8-202052 a remover solution composition for resist which is free from the above drawbacks and comprises hydrofluoric acid optionally containing ammonium fluoride, i.e., so-called buffered hydrofluoric acid, a water-soluble organic solvent, and an anticorrosive. However, since the above remover solution composition for resist contains hydrofluoric acid, it is not quite safe for the human body and is difficult to handle. Furthermore, since the above composition is acidic, it is apt to corrode peripheral devices including remover solution feed facilities which connect a removing tank to a remover container. Other drawbacks of the above composition include the necessity of troublesome treatments of exhaust and wastewater of the remover solution composition for resist.